Automotive electronics module

ABSTRACT

A hermetically sealed automotive module is disclosed wherein a cover of the module is sealed to a housing of the module by vibration welding. A weld contact surface is defined between the cover and housing of the module when the cover and housing undergo relative reciprocating motion under the application of a force. A method for hermetically sealing a module is also disclosed.

This is a division of application Ser. No. 07/779,750, filed Oct. 21,1991, U.S. Pat. No. 5,264,661.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to automotive electronic controlmodules. More particularly, the present invention relates to anautomotive electronic module enclosing electronic circuitry which issealed hermetically by vibration welding.

2. Disclosure Information

Automotive underhood electronic modules typically contain delicatecircuitry such as integrated circuits, power circuit boards and the likeused in various operating systems within the vehicle, such as ananti-lock brake system, an engine control system, multiplex system andothers. During use, these modules are subjected to extremely harshconditions such as heat, moisture, and vibration which could havedeleterious effects upon the circuitry within the module if the modulesare not sealed. Typically, the modules are sealed with a glue such asshown in U.S. Pat. No. 3,909,504 and/or are filled with a resin orpotting material, such as shown in U.S. Pat. Nos. 4,546,412 and4,899,257. Glueing processes are used in sealing the modules to controlthe amount of vibration imposed on the module to limit damage to thedelicate circuitry inside. However, glueing the modules to seal them isa time-consuming manufacturing process. It would be advantageous toprovide an alternative manufacturing process for sealing the modules.

Vibration welding, or friction welding, is a manufacturing process bywhich two work pieces are reciprocated linearly relative to one anotherunder the application of a force, causing the mating surfaces of thework pieces to soften under the influence of friction. After a weld timeinterval, the work pieces are returned to their original position andthey are held in forced contact for a sufficient length of time for themating surfaces to solidify. Upon solidification, the force ceases andthe work pieces are bonded together. Such a technique is shown in U.S.Pat. No. 4,377,428. It has been heretofore unknown to use vibrationwelding to seal hermetically an electronics control module for a vehiclebecause of the potential damage which may be inflicted upon the internalcircuitry of the module during the relative vibration of the sealingparts.

It is an object of the present invention to seal hermetically automotiveelectronic modules containing delicate electronic circuitry therein byvibration welding. These and other objects, features and advantages ofthe present invention will become apparent from the following summary,description, and claims which follow.

SUMMARY OF THE INVENTION

The present invention provides a method for hermetically sealing anautomotive electronics module enclosing electronics circuitry, themodule including a housing for receiving the circuitry therein, meansdisposed in the housing for providing electrical connection between thecircuitry and the vehicle, and a cover enclosing the means and thehousing, the method comprising the steps of: assembling the circuitryand the connection means in the housing; supporting the housing in afirst support means and supporting the cover in a second support meansto dispose a planar portion of the cover in abutting contact with acircumferential edge of the housing. The method further comprises thesteps of applying a force to the cover in a direction parallel to thelongitudinal axis of the housing for causing the cover to be in abuttingsurface contact with the circumferential edge of the housing and causingthe first and second support means to undergo relative linearreciprocating motion along an axis perpendicular to the longitudinalaxis of the housing during a predetermined weld-time interval forcausing thermoplastic material along the respective abutting contactsurfaces to melt to form a first-weld surface, and upon cessation of thereciprocating motion, to rigidify the first-weld surface whereby thecover becomes welded to the housing along the weld surface.

There is also provided herein an automotive module for enclosingelectronic circuitry therein comprising a housing having a closed endand an open end and a receiving volume defined therebetween forreceiving the circuitry therein, the open end including acircumferential edge extending therearound. The module further includesa cover for enclosing the housing, the cover being welded to the housingalong an abutting contact surface between the planar portion of saidcover and the circumferential edge of the housing by vibration welding.In one embodiment of the invention, the module may further includeconnector means for providing electrical connection between the moduleand the vehicle, the connector including a circumferential lip extendingtherearound and adapted to be in abutting surface contact with theplanar portion of the cover. In this embodiment, the cover can be weldedsimultaneously to the circumferential lip of the connector means and thecircumferential edge of the housing along two weld contact surfaces byvibration welding.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an automotive electronic control modulestructured in accord with the principles of the present invention;

FIG. 2 is an exploded view of the module of FIG. 1;

FIG. 3 is an enlarged view of a section of the module of FIG. 1 takenalong line 3--3;

FIG. 4 is an enlarged view of the section of the module of FIG. 1 takenalong line 3--3 before the assembly of the module.

FIGS. 5, 6, and 7 are cross sectional views of an upper portion of themodule of FIG. 1 showing the succeeding stages of hermetically sealingthe module in accordance with the principles of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to the drawings, FIG. 1 shows a perspective view of ananti-lock brake system electronics control module 10 which encloseselectronic circuitry for controlling an anti-lock brake system of avehicle. It should be readily apparent to those skilled in the art thatthe present invention is not meant to be limited solely to an anti-lockbrake system module as described hereinafter, but may suitably beemployed with various other automotive modules, such as engine controlmodules, multiplex modules and the like. The anti-lock brake systemmodule 10 will be used as an example only in the description of thepresent invention. The module 10 is fabricated from a thermoplasticmaterial, such as ABS, glass-filled nylon, polyester, polypropylene orany of a number of known thermoplastic materials suitable for use in theunderhood environment of an automobile.

The module 10 comprises a housing 12 which receives the electroniccircuitry therein and a connector 14 for providing electrical connectionbetween the electronic circuitry in the housing 12 and the vehicle. Themodule also includes a cover 16 for enclosing the module.

As shown in FIG. 2, the housing 12 includes a closed-end 18, an open-end20 and a receiving volume 22 defined therebetween for receiving theelectronic circuitry therein. The open-end 20 of housing 12 includes acircumferential edge 24 extending therearound. A pair of locking tabs 26depend from the circumferential edge 24 temporarily hold the controlmodule assembly together prior to the sealing of the module. The housing12 also includes a pair of securing tabs 28 having apertures 30 thereinfor receiving threaded fasteners therethrough to connect the module 10to the vehicle.

The receiving volume 22 is configured to receive the electroniccircuitry, such as shown at 32. In the anti-lock brake system moduledescribed in FIG. 2, the electronic circuitry includes a power circuitboard 34 containing the control electronics, such as are commonly knownin the art. The circuit board is connected to a heat sink 36, typicallymanufactured of extruded or die cast aluminum as well as a plurality ofconnector pins 38. The connector pins 38 provide electrical connectionmeans between the circuit board 34 and a mating male connector (notshown) disposed in the vehicle. The circuit board 34 is connectedtypically to the heat sink through the use of screws or clips, althoughthe present invention is not meant to be limited to the circuitrydescribed herein.

The module 10 shown in FIG. 1 further includes a connector 14 having abase portion 40 and a rectangular vertical wall 42 projectingperpendicularly therefrom. The vertical wall 42 defines a volume 44 intowhich a male mating connector is disposed to connect the vehicle to thecontrol module 10. As such, the connector 14 provides connection meansfor providing electrical connection between the module and the vehicle.The connector 14 further includes a circumferential lip 46 extendingtherearound. As can be seen in FIG. 4, the circumferential lip 46 causesa space (d) between the cover 16 and the housing 12 in the assembled,but unsealed condition as will be described below.

The circumferential lip 46 of the connector is configured to abut agenerally planar portion 48 of the cover 16. The cover 16 is a generallyplanar member having the planar portion 48 and an aperture 50 definedtherein through which pass the vertical walls 42 of the connector 14.The cover 16 also includes a pair of locking clips 52 having anelongated slot 54 therein for mating engagement with the tabs 26 of thehousing 12. The clips 52 temporarily hold the module 10 into anassembled condition prior to the hermetic sealing of the module by themethod of the present invention. As can be seen in FIGS. 3 and 4, theelongated slot 54 has a length greater than the length of the tabs 26 ofthe housing 12. As will be explained herein, this allows for therelative linear reciprocal movement of the cover 16 and the housing 12.

FIGS. 5, 6 and 7, show a cross-sectional view of the upper portion ofthe module 10 of FIG. 1 in the succeeding stages of sealing the module10 according to the method of the present invention. FIG. 5 shows themodule 10 in an assembled, but unsealed condition, wherein the clips 52of the cover 16 have engaged the locking tabs 26 of the housing. In FIG.5, the cover 16 is shown as being press fit or interference fitted intoan upper platen 56 of a vibration welding machine while the housing 12is fit by an interference fit into a lower platen 58 of the vibrationwelding machine. As such, the upper platen 56 and lower platen 58comprise a first and second support means configured to undergo relativelinear reciprocating motion along an axis perpendicular to thelongitudinal axis of the housing (A) during the vibration welding of themodule.

The circumferential lip 46 of the connector 14 and the planar portion 48of the cover 16 define a first abutting contact surface 60 resulting inthe spacing (d) described earlier. During the method of the presentinvention, after the electronic circuitry 32, the connector 14 and thecover 16 have been locked into the assembled condition by the matingengagement of the clips 52 and locking tabs 26, the upper platen 56 andlower platen 58 reciprocate linearly relative to one another along anaxis (A) perpendicular to the longitudinal axis of the housing (A) for aweld time of between one and three seconds. The upper platen provides aforce, relative to the lower platen, sufficient to produce a pressure atthe weld contact surface of between 200-250 pounds per square inch,while the upper platen 56 reciprocates at at a minimum frequency of 150Hz. In the preferred embodiment, the upper platen 56 reciprocatesrelative to the lower platen 58 at an approximate frequency of 240 Hz.The application of the force causes the abutting contact surface 60 tomelt forming a weld contact surface 62 between the circumferential lip46 of the connector 14 and the planar portion 48 of the cover 16 asshown at 62 in FIG. 6. When the weld contact surface 62 is formed, asecond abutting contact surface 64 is defined between thecircumferential edge 24 of the housing 12 and the planar portion 48 ofthe cover 16. While the weld at contact surface 62 is still molten, theupper platen 56 and lower platen 58 maintain the reciprocal linearmotion while still maintaining the predetermined applied force. Thiscauses the weld contact surface 62 to remain molten while a second weldcontact surface, 66 in FIG. 7, is formed between the circumferentialedge 24 of housing 12 and the planar portion 48 of the cover 16. After apredetermined weld time interval of between 1-3 seconds, during whichweld time the relative linear reciprocating motion of the upper andlower planes as well as the force between the upper and lower planes aremaintained, the reciprocating motion is stopped but the force ismaintained until the first and second weld surfaces can rigidify, inapproximately one second. After the first and second weld surfaces 62,64 have rigidified, the cover 16 becomes simultaneously welded to theconnector 14 and the housing 12 along two weld surfaces, 62, 64. Theupper and lower platens are moved apart and the module is then removedfrom the lower platen and is ready to be installed into a vehicle.

Various modifications and alterations of the present invention will bereadily apparent to those of skill in the art. For example, the cover ofthe module may be sealed hermetically to a housing directly, without theintermediate step of sealing the cover to a connector. This would havebeneficial use in modules wherein a connector such as that shown in thedetailed description is unnecessary. Accordingly, it is the followingclaims, including all equivalents, which define the scope of the presentinvention.

What is claimed is:
 1. A method for hermetically sealing an automotiveelectronics module enclosing electronic circuitry, said module includinga housing for receiving the circuitry therein, connection means disposedin said housing for providing electrical connection between saidcircuitry and the vehicle, and a cover enclosing said connection meansand said housing, the method comprising the steps of:assembling saidcircuitry and said connection means in said housing; supporting saidhousing in a first support means; supporting said cover in a secondsupport means to dispose a planar portion of said cover in abuttingcontact with a circumferential edge of said housing; applying a force tosaid cover in a direction parallel to the longitudinal axis of saidhousing for causing said cover to be in abutting surface contact withsaid circumferential edge; causing said first and second support meansto undergo relative linear reciprocating motion along an axisperpendicular to the longitudinal axis of said housing during apredetermined weld time interval for causing thermoplastic materialalong said respective abutting contact surfaces to melt to form a firstweld surface, and upon cessation of said reciprocating motion, torigidify said first weld surface, whereby said cover
 2. A methodaccording to claim 1, wherein the step of reciprocating said first andsecond support means relative one another occurs at a frequency greaterthan 150 Hz.
 3. A method according to claim 2, wherein the step ofreciprocating said first and second support means occurs for a minimumtime interval of one second.
 4. A method according to claim 3, whereinthe step step of applying a force to said cover includes applying aminimum pressure of 200 pounds per square inch at the weld contactsurface. becomes welded to said housing along said first weld surface.5. A method for hermetically sealing an automotive electronics moduleenclosing electronic circuitry, said module including a housing forreceiving the circuitry therein, a connector disposed in said housingand providing electrical connection between said circuitry and thevehicle, and a cover enclosing said connector and said housing, themethod comprising the steps of:assembling said circuitry and saidconnector in said housing; supporting said housing in a first supportmeans; supporting said cover in a second support means to dispose aplanar portion of said cover in abutting contact with a circumferentiallip of said connector; applying a force to said cover in a directionparallel to the longitudinal axis of said housing for causing said coverto be in abutting surface contact with said circumferential lip; causingsaid first and second support means to undergo relative linearreciprocating motion along an axis perpendicular to the longitudinalaxis of said housing during a predetermined weld time interval forcausing thermoplastic material along said respective abutting surfacecontacts to melt to form a first weld surface; maintaining said force tosaid cover for causing said planar portion of said cover to be inabutting surface contact with a circumferential edge of said housingwhile said first weld surface is molten to form a second weld surface;maintaining said relative linear reciprocating motion of said first andsecond support means during said weld time interval for causingthermoplastic material along said respective abutting surfaces of saidplanar portion and said circumferential edge to melt and upon cessationof said reciprocating motion, to rigidify both said first and secondweld surfaces whereby said cover becomes simultaneously welded to saidconnector and said housing along two weld surfaces.
 6. A methodaccording to claim 5, wherein the step of reciprocating said first andsecond support means relative one another occurs at a frequency between200 Hz and 250 Hz.
 7. A method according to claim 6, wherein the step ofreciprocating said first and second support means occurs for a timeinterval of between one and three seconds.
 8. A method according toclaim 7, wherein the step of applying a force to said cover furtherincludes providing a pressure of 240 pounds per square inch.